Sintered materials having a composition according to the formula LnBa.sub.2 Cu.sub.3 O.sub.7-.delta. are already known as superconductive substances. Such sintered materials are produced from a powder mixture comprising an oxide of a rare earth element (Ln.sub.2 O.sub.3), barium carbonate (BaCO.sub.3) and copper oxide (CuO) by blending and milling the powder mixture, pre-sintering the resulting powder, again milling the pre-sintered product, press-shaping the resulting powder and sintering the shaped product.
However, the conventional powder process has the following problems:
(a) since an oxide or a carbonate is used as a starting material, the synthesized product often is nonhomogeneous and the removal of the impurities is difficult. Accordingly, superconductive substances having a high purity and a uniform composition were difficult to obtain, and superconductive substances with improved characteristics are needed,
(b) in practice, because the process includes the sintering of a powder, the ability to shape the material is poor and it is difficult to obtain superconductive substances with a desired shape. In particular, it is extremely difficult to manufacture filmy or fibrous superconductive substances, and
(c) the sintering step requires heating to relatively high temperatures, and the manufacturing costs are therefore high.
The present invention provides a method for preparing superconductive substances in shapes, which are difficult to manufacture by other conventional processes. In addition, superconductive substances of high purity can be produced by the method of the present invention.